Seven Sleepers Day (Siebenschläfertag) is a feast day observed in Germany on June 27 each year. It commemorates the Christian legend about the Seven Sleepers of Ephesus.

The Seven Sleepers of Ephesus were a group of youth who were persecuted for being Christian during the reign of the Roman emperor Decius. They hid in a cave near Ephesus to escape and fell asleep. They awoke only 180 years later, when Christians were not persecuted in the Roman Empire anymore.

Seven Sleepers Day was declared a commemoration day in the Middle Ages. There is a traditional weather lore associated with it. The weather on the day is supposed to determine the average weather conditions of the following seven weeks.

Contrary to popular belief, Seven Sleepers Day has nothing to do with the edible dormouse that is called Siebenschläfer in Germany.

There is some confusion as to whether Seven Sleepers Day should still be celebrated on June 27. The weather lore associated with the day had emerged before the Gregorian calendar reform that occurred in 1582.

Taking into account the difference between the Gregorian calendar and the Julian calendar, Seven Sleepers Day should be celebrated on July 7 instead of June 27. Nevertheless, it's date hasn't changed since the reform, it is observed on the same day as before.